Results for “grain mapping” — Page 12

NASA NTRS1972

ERTS-1 imagery of eastern Africa: A first look at the geological structure of selected areas

The author has identified the following significant results. Imagery of the African rift system resolves the major Cainozoic faults, zones of warping, and associated volcanism. It also clearly depicts the crystal grain of the Precambrian rocks where these are exposed. New structural features, or new properties of known features such as greater extent, continuity, and linearity are revealed by ERTS-1 imagery. This applies, for example, to the NE-SW fracture zones in Yemen, the Aswa mylonite zone at the northern end of the Western Rift, the Nandi fault of western Kenya, the linear faults of the Elgeyo escarpment in the Gregory Rift, and the hemibasins of warped Tertiary lavas on the Red Sea margin of Yemen, matching those of Ethiopian plateau-Afar margin. A tentative scheme is proposed, relating the effect on the pattern of Cainozoic faulting of the degree of obliquity to Precambrian structural trend. It is particularly noteworthy that, even where the Precambrian grain determines the rift faulting to be markedly oblique to the overall trend of the rift trough, for example, in central Lake Tanganyika, the width of the trough is not significantly increased. Some ground mapped lithological boundaries are obscure on ERTS-1 imagery.

Mohr, P. A.↗

NASA NTRS1984

Snow Reflectance from LANDSAT-4 Thematic Mapper

In California 75% of the agricultural water supply comes from the melting Sierra Nevada snowpack. Basin-wide albedo measurements from the LANDSAT-4 Thematic Mapper could be used to better forecast the timing of the spring runoff, because these data can be combined with solar radiation calculations to estimate the net radiation budget. The TM is better-suited for this purpose than the MSS because of its large dynamic range. Saturation still occurs in bands 1-4, but is severe only in band 1. Differentiation of snow optical grain size is possible with TM band 4 through a moderately clear atmosphere. The TM band 5 can discriminate clouds from snow, and the combination of bands 2 and 5 appears best for snow mapping.

Dozier, J.↗

NASA NTRS2013

Allochthonous Addition of Meteoritic Organics to the Lunar Regolith

Preparation of lunar samples 74220,861 was discussed in detail in [3, 4]. Our analysis sequence was as follows: optical microscopy, UV fluorescence imaging, -Raman, FESEM-EDX imaging and mapping, FETEMEDX imaging and mapping of a Focused Ion Beam (FIB) extracted section, and NanoSIMs analysis. We observed fluffytextured C-rich regions of interest (ROI) on three different volcanic glass beads. Each ROI was several m2 in size and fluoresced when exposed to UV. Using FESEM/EDX, the largest ROI measured ~36 m and was located on an edge of a plateau located on the uppermost surface of the bead. The ROI was covered on one edge by a siliceous filament emanating from the plateau surface indicating it was attached to the bead while on the Moon. EDX mapping of the ROI shows it is composed primarily of heterogeneously distributed C. Embedded with the carbonaceous phase are localized concentrations of Si, Fe, Al and Ti indicating the presence of glass and/or minerals grains. -Raman showed strong D- and G-bands and their associated second order bands; intensity and location of these bands indicates the carbonaceous matter is structurally disorganized. A TEM thin section was extracted from the surface of a glass bead using FIB microscopy. High resolution TEM imaging and selected area electron diffraction demonstrate the carbonaceous layer to be amorphous; it lacked any long or short range order characteristic of micro- or nanocrystalline graphite. Additionally TEM imaging also revealed the presence of submicron mineral grains, typically < 50 nm in size, dispersed within the carbonaceous layer. NanoSIMs data will be presented and discussed at the meeting. Given the noted similarities between the carbonaceous matter present on 74220 glass beads and meteoritic kerogen, we suggest the allochthonous addition of meteoritic organics as the most probable source for the C-rich ROIs.

Thomas-Keprta, K. L.↗

NASA NTRS1992

Polarimetric observations of comet Levy 1990c and of other comets: Some clues to the evolution of cometary dust

The evolution with the phase angle alpha of the polarization degree P of light scattered by comet Halley's dust is well documented. No significant discrepancy is found between Halley and Levy polarization curves near the inversion point. From all available cometary observations, we have derived polarimetric synthetic curves. Typically, a set of about 200 data points in the red wavelengths range exhibits a minimum for (alpha approximately equals 10.3 degrees, P approximately equals 1.8 percent) and an inversion point for (alpha approximately equals 22.4 degrees, P = 0 percent), with a slop of about 0.27 percent per degree. A significant spreading of some data (comets Austin 1982VI, Austin 1989c1, West 1976VI) is found at large phase angles. The analysis of our polarimetric maps of Levy reveals that the inner coma is heterogeneous. The increase of the inversion angle value with increasing distance from the photometric center is suspected to be due to the evolution with time of grains ejected from the nucleus. A fan like structure could be produced by a jet of grains freshly ejected.

Levasseur-Regourd, Anny-Chantal↗

DOE OSTI2026

A Robotic High-Throughput Grid-Search Platform for Mapping Phase Behavior in Triblock Copolymer–Homopolymer Blends

We present a high-throughput experimental investigation of the phase behavior in triblock copolymers (PS-b-PB-b-PS and PS-b-PI-b-PS) and polystyrene (PS) homopolymer blends as a function of homopolymer molecular weight (MW) and blend ratio. Using a robotic thin-film processing platform (NOVA) integrated with Grazing Incidence Small-Angle X-ray Scattering (GISAXS) and Atomic Force Microscopy (AFM), we systematically mapped the order–disorder transition (ODT) boundaries and domain spacing evolution across a broad MW range (4.0–101.3 kDa) with varying homopolymer loadings (10% to 90%). The results reveal three distinct regimes: low-MW homopolymers, corresponding to the wet-brush regime produced only gradual domain swelling before disordering at high blend ratios (weight fraction); medium-MW homopolymers, corresponding to thedry-brush regime induced significant domain spacing increase up to 80% followed by earlier disordering, while high-MW homopolymers led to macrophase separation with minimal changes in domain spacing. Additionally, coarse-grained molecular dynamics simulations confirmed our experimental finding that in the low-MW region, the PS homopolymer uniformly distributed in the PS domain. These findings demonstrate that homopolymer molecular weight critically governs both the extent of domain swelling and the onset of disorder in triblock copolymer systems. This high-throughput platform enables the rapid mapping of composition–morphology relationships and can be integrated with AI/ML tools for designing next-generation nanostructured polymers.

36 MATERIALS SCIENCE↗

DOE OSTI2025

The Martini 3 Lipidome: Expanded and Refined Parameters Improve Lipid Phase Behavior

Lipid membranes are central to cellular life. Complementing experiments, computational modeling has been essential in unraveling complex lipid-biomolecule interactions, crucial in both academia and industry. The Martini model, a coarse-grained force field for efficient molecular dynamics simulations, is widely used to study membrane phenomena but has faced limitations, particularly in capturing realistic lipid phase behavior. Here, we present refined Martini 3 lipid models with a mapping scheme that distinguishes lipid tails that differ by just two carbon atoms, enhancing the structural resolution and thermodynamic accuracy of model membrane systems including ternary mixtures. The expanded Martini lipid library includes thousands of models, enabling simulations of complex and biologically relevant systems. These advancements establish Martini as a robust platform for lipid-based simulations across diverse fields.

Lipids↗

DOE OSTI2024

ICED: An Integrated CGRA Framework Enabling DFVS-Aware Acceleration

oarse-grained reconfigurable arrays (CGRAs) are a promising solution to enable energy-efficient acceleration of applications from different domains. By leveraging reconfiguration at the functional level, they can adapt to significantly different computational patterns. Existing CGRA mapping approaches extract instruction-level parallelism, exploit loop-pipelining opportunities, guarantee the data dependency, and target high throughput of a given loop. However, the recurrence data-dependency in the DFG and the mismatch between required and available computing/communication resources complicate the mapping, and might lead to significant unbalances in the utilization of the CGRA's tiles. This results in wasted power for tiles with low utilization. Applying dynamic voltage and frequency scaling (DVFS) can potentially solve this challenge and improve energy efficiency by adjusting voltage and frequency of different tiles independently. CGRAs have also been successful in accelerating data-dependent streaming applications. However, in these applications, the execution time of each kernel in the pipeline might dynamically vary depending on the characteristics of the input. This also leads to under-utilization of resources for the dynamically changing kernels that do not limit the application throughput. DVFS can also improve energy efficiency for these applications by dynamically changing the voltage and frequency levels of tiles that host non performance-constraining kernels. This paper proposes ICEDTEA -- an integrated DVFS-aware framework to map applications on CGRAs that support power islands. ICEDTEA proposes a CGRA architecture supporting DVFS islands at varying granularity (from a single tile to a group of tiles) and the related DVFS-aware compilation and mapping toolchain. ICEDTEA is the first work that introduces DVFS support for spatio-temporal CGRAs at power-island levels. The experimental evaluation shows that ICEDTEA improves average utilization by 2.3$\times$ and energy-efficiency by 1.32$\times$ over a conventional CGRA. With streaming applications, ICEDTEA improves energy efficiency by 1.12$\times$ over a state-of-the-art CGRA that introduces partial dynamic reconfiguration to adapt to variations in kernels' throughput.

Tan, Cheng↗

DOE OSTI2026

Mechanism-Resolved PFM of Ferroionic and Ferroelectric Responses in Thickness-Gradient Hf 0.5 Zr 0.5 O 2 Libraries

Resolving growth mechanisms and thickness evolution of functional properties is one of the key tasks in materials discovery and optimization involving thin-film materials, traditionally requiring significant experimental budgets. Here we introduce the combination of thickness-gradient libraries and automated scanning probe microscopy as a systematic pathway to elucidate growth modes and disentangle ferroelectric and electrochemical contributions in ferroelectric thin films. As a model system, we explore the Hf 0.5 Zr 0.5 O 2 (HZO) gradient thin films grown on La x Sr 1-x MnO 3 (LSMO) bottom electrode thin films. Automated piezoresponse force microscopy, spectroscopy, and lithography reveals that irreversible topographic deformation arises from electrochemical activity at the LSMO surface, whereas reversible phase inversion in HZO reflects ferroelectric switching. Automated topography height-map scans are used to further quantify nucleation density, particle-size evolution, and roughness correlations across the thickness-gradient, demonstrating that improved plume stabilization during growth suppresses interfacial reactions and promotes dense, fine-grained HZO conducive to ferroelectric phase formation. This combined materials-engineering and automated-SPM framework establishes a platform for high-throughput, mechanism-resolved characterization of ferroionic and ferroelectric responses in complex oxide films.

FOS: Physical sciences↗

NASA NTRS2004

The History of Presolar Grains

Below we summarize the results of our investigations into the history of presolar grains that were conducted in the last year. During this time we have expended much of our effort in the development of experimental techniques and sample preparation methods that are needed to laboratory in December, 2000. Specific information on this instrument is contained in the Full Proposal of PI Ernst Zinner and will not be repeated here. Our general strategy in the past year has been in large measure to explore novel sample handling methods for the very small (sub-micron), but more representative, presolar grains that can now be characterized isotopically in the NanoSIMS. We have developed experimental techniques that will permit NanoSIMS analyses of the very same ultramicrotome sections studied in the TEM, and we have developed grain dispersion, handling and mounting techniques that permit NanoSIMS isotopic analysis as well as field emission SEM, high energy TEM, and atomic force microscopy of pristine presolar grains. Although much of this has been slow and very difficult work that has no immediate payoff in terms of publishable results, we considered it absolutely necessary groundwork for future discoveries, especially in the realm of individual presolar grains that have been inaccessible to past studies due to size constraints. As discussed below, we have been largely successful in these endeavors, and expect to reap the benefits of this work in the next year. We also report on our continued morphologic studies of pristine presolar grains, on our investigations of presolar graphite grains from supernovae as well as on rarer types of presotar SIC, on the search for presolar silicates, and on our efforts to obtain direct size-distribution information on presolar SiC through X-ray mapping techniques.

Bernatowicz, Thomas J.↗

NASA NTRS1989

Dust emission from high latitude cirrus clouds

In order to study dust emission from grains in the interstellar medium, the infrared properties were analyzed in a number of isolated high latitude dust clouds which contain no dominant internal heating sources. The clouds are spatially resolved, have a simple geometry, and are mapped in the IRAS bands at 12, 25, 60, and 100 microns. For a number of these clouds, extinction data (A sub B) were obtained from starcounts. A large part (30 to 50 percent) of the infrared radiation of the clouds in the IRAS wavelength range of 8 to 130 micron is emitted in the short wavelength bands at 12 and 25 micron. The 60/100 micron ratios for the integrated fluxes of the clouds have a typical value of 0.19 + or - 0.05.

Laureijs, Rene J.↗

NASA NTRS1998

An Assessment of the Axial and Radial Dilation of a DPIMS Tantalum Cartridge for Space Shuttle Flight Experiments

Ground-based heat treatment tests are planned on an argon gas-filled tantalum cartridge developed as pan of a Diffusion Processes in Molten Semiconductors (DPIMS) experiment conducted on NASA's Space Shuttle. The possibility that the cartridge may creep during testing and touch the furnace walls is of real concern in this program. The present paper discusses the results of calculations performed to evaluate this possibility. Deformation mechanism maps were constructed using literature data in order to identify the creep mechanism dominant under the appropriate stresses and temperatures corresponding to the test conditions. These results showed that power-law creep was dominant when the grain size of the material exceeded 55 gm but Coble creep was the important mechanism below this value of grain size. Finite element analysis was used to analyze the heat treatment tWs assuming a furnace run away condition (which is a worst case scenario) using the appropriate creep parameters corresponding to grain sizes of 1 and 100 gm. Calculations were also conducted to simulate the effect of an initial 3 tilt of the cartridge assembly, the maximum possible tilt angle. The von Mises stress and su-ain distributions were calculated assuming that the cartridge was fixed at one end as it was heated from ambient temperature to 1823 K in 1.42 h, maintained at 1823 K for 9.5 h and then further heated to an over temperature condition of 2028 K in 0.3 h. The inelastic axial and radial displacements of the cartridge walls were evaluated by resolving the von Mises strain along the corresponding directions. These calculations reveal that the maximum axial and radial displacements are expected to be about 2.9 and 0.25 mm, respectively, for both fine and coarse-grained materials at 2028 K. It was determined that these displacements occur during heat-up to temperature and creep of the cartridge is likely to be relatively insignificant irrespective of grain size. Furthermore, with a 3' tilt of the cartridge, the deflection is increased by only 0.39 gm which is negligible. Since the gap between the furnace heating elements and the cartridge is about 7.5 mm and less than the maximum radial dilation of 0.25 mm at 2028 K, it is concluded that the cartridge is unlikely to touch the furnace walls during the experiments.

Raj, S.V.↗

DOE OSTI2024

Microscopic understanding of the effects of impurities in low RRR SRF cavities

The SRF community has shown that introducing certain impurities into high-purity niobium can improve quality factors and accelerating gradients. We question why some impurities improve RF performance while others hinder it. The purpose of this study is to characterize the impurities of niobium coupons with a low residual resistance ratio (RRR) and correlate these impurities with the RF performance of low RRR cavities so that the mechanism of impurity-based improvements can be better understood and improved upon. The combination of RF testing, temperature mapping, frequency vs temperature analysis, and materials studies reveals a microscopic picture of why low RRR cavities experience low BCS resistance behavior more prominently than their high RRR counterparts. We evaluate how differences in the mean free path, grain structure, and impurity profile affect RF performance. The results of this study have the potential to unlock a new understanding on SRF materials and enable the next generation of high Q/high gradient surface treatments.

43 PARTICLE ACCELERATORS↗

DOE OSTI2024

Microscopic Understanding of the Effects of Impurities in Low RRR SRF Cavities

The SRF community has shown that introducing certain impurities into high-purity niobium can improve quality factors and accelerating gradients. We question why some impurities improve RF performance while others hinder it. The purpose of this study is to characterize the impurities of niobium coupons with a low residual resistance ratio (RRR) and correlate these impurities with the RF performance of low RRR cavities so that the mechanism of impurity-based improvements can be better understood and improved upon. The combination of RF testing, temperature mapping, frequency vs temperature analysis, and materials studies reveals a microscopic picture of why low RRR cavities experience low BCS resistance behavior more prominently than their high RRR counterparts. We evaluate how differences in the mean free path, grain structure, and impurity profile affect RF performance. The results of this study have the potential to unlock a new understanding on SRF materials and enable the next generation of high Q/high gradient surface treatments.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

DOE OSTI2024

Microscopic Understanding of the Effects of Impurities in Low RRR SRF Cavities

The SRF community has shown that introducing certain impurities into high-purity niobium can improve quality factors and accelerating gradients. We question why some impurities improve RF performance while others hinder it. The purpose of this study is to characterize the impurities of niobium coupons with a low residual resistance ratio (RRR) and correlate these impurities with the RF performance of low RRR cavities so that the mechanism of impurity-based improvements can be better understood and improved upon. The combination of RF testing, temperature mapping, frequency vs temperature analysis, and materials studies reveals a microscopic picture of why low RRR cavities experience low BCS resistance behavior more prominently than their high RRR counterparts. We evaluate how differences in the mean free path, grain structure, and impurity profile affect RF performance. The results of this study have the potential to unlock a new understanding on SRF materials and enable the next generation of high Q/high gradient surface treatments.

Howard, K.↗

DOE OSTI2024

Microscopic understanding of the effects of impurities in low RRR SRF cavities

The SRF community has shown that introducing certain impurities into high-purity niobium can improve quality factors and accelerating gradients. We question why some impurities improve RF performance while others hinder it. The purpose of this study is to characterize the impurities of niobium coupons with a low residual resistance ratio (RRR) and correlate these impurities with the RF performance of low RRR cavities so that the mechanism of impurity-based improvements can be better understood and improved upon. The combination of RF testing, temperature mapping, frequency vs temperature analysis, and materials studies reveals a microscopic picture of why low RRR cavities experience low BCS resistance behavior more prominently than their high RRR counterparts. We evaluate how differences in the mean free path, grain structure, and impurity profile affect RF performance. The results of this study have the potential to unlock a new understanding on SRF materials and enable the next generation of high Q/high gradient surface treatments.

Howard, K.↗

NASA NTRS1994

Atomic and molecular gas in interstellar cirrus clouds

The dust, atomic gas, and molecular gas content of a sample of 26 of isolated, degree-sized infrared clouds are compared. Half of the clouds have an infrared excess indicating the presence of H2, and 14 contain compact CO-emitting regions. Complete, high angular resolution H I and CO maps of one cloud, G236+39, resolve the transition between atomic and molecular H, as well as the location of CO formation. Assuming the infrared emission traces the total column density, H2 is inferred to be much more widely distributed than the CO. The CO rotational levels are subthermally excited, and the (2 - 1)/(1 - 0) line ratios suggest a density n(H2) approximately 200/cm(exp 3) where CO was detected. A model of H2 formation on grain surfaces balanced by self-shielded photodissociation fits the variation of infrared brightness with H I column density. Assuming a temperature of 80 K, typical of diffuse H2 (Savage et al. 1977), the H2 chemistry requires an average density n(H + 2H2) approximately 50/cm(exp 3). For G236+39, if the distance is 100 pc, the H I and H2 masses are estimated to be 90 and 70 solar mass, respectively. High-resolution H I and infrared maps of a smaller cloud, G249.0+73.7, reveal no evidence for molecular gas, which is likely due to the low total column density through this cloud. These results suggest the H2 and H I content are comparable for some interstellar cirrus clouds with column densities N(H I) greater than 4 x 10(exp 20)/cm(exp 2), even where CO was not detected.

Reach, William T.↗

DOE OSTI2025

Complexions at the iron-magnetite interface

Synthesizing distinct phases and controlling crystalline defects are key concepts in materials design. These approaches are often decoupled, with the former grounded in equilibrium thermodynamics and the latter in nonequilibrium kinetics. By unifying them through defect phase diagrams, we can apply phase equilibrium models to thermodynamically evaluate defects—including dislocations, grain boundaries, and phase boundaries—establishing a theoretical framework linking material imperfections to properties. Using scanning transmission electron microscopy (STEM) with differential phase contrast (DPC) imaging, we achieve the simultaneous imaging of heavy Fe and light O atoms, precisely mapping the atomic structure and chemical composition at the iron-magnetite (Fe/Fe 3 O 4 ) interface. We identify a well-ordered two-layer interface-stabilized phase state (referred to as complexion) at the Fe[001]/Fe 3 O 4 [001] interface. Using density-functional theory (DFT), we explain the observed complexion and map out various interface-stabilized phases as a function of the O chemical potential. The formation of complexions increases interface adhesion by 20% and alters charge transfer between adjacent materials, impacting transport properties. Our findings highlight the potential of tunable defect-stabilized phase states as a degree of freedom in materials design, enabling optimized corrosion protection, catalysis, and redox-driven phase transitions, with applications in materials sustainability, efficient energy conversion, and green steel production.

36 MATERIALS SCIENCE↗

NASA NTRS1979

Comparison of single crack propagation in lunar analogue glass and the failure strength of rocks

New data of crack propagation in lunar analogue glass provides important input for the construction of deformation maps (maps which delineate the rates and principal means of material deformation under various environmental conditions) applicable to the lunar crust. Comparison of single crack propagation data obtained on flat plates of glass and failure strength data obtained on fine grained rock samples show that single crack propagation velocities are directly related to the failure strength of rocks. The chemical reaction between water and silicon-oxygen bonds at the crack tip seems to be of first order. This greatly simplifies extrapolation to low partial pressures of H2O

Soga, N.↗